Image being magnified in preview
 

I have code that embeds a signature image in an email's footer. VSTO 2008 C#
OL2007.

For some reason Outlook 2007 magnifies the image a whole lot (e.g. if I send
the email to myself and look at the image/email in the email preview pane)
and
therefore it loses clarity.

If I then hold down the CTRL key and mouse-wheel down 2 clicks it goes to
the original size. However it then makes the email body-text tiny.

Anyone know why this is? Anyone know how I can stop Outlook from behaving
that way?

I have checked the View Source and see the width and height for the image
tag matches the pixel width and height of the png correctly. When I open the
same email in Windows Mail it appears fine.